A Study of bbT369 in Relapsed and/or Refractory B Cell Non-Hodgkin's Lymphoma (NHL)

Inclusion Criteria: * ≥18 years of age at the time of signing informed consent. * Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2. * Diagnosis of B-cell NHL according to WHO 2017 classification or WHO 2016 classification where applicable: 1. DLBCL (germinal center B cell \[GCB\] or activated B cell \[ABC\] type or not otherwise specified \[NOS\]) 2. HGBCL (with MYC and BCL2 and/or BCL6 rearrangements or NOS) 3. PMBCL 4. FL 3b 5. DLBCL transformed from FL * Participants must have relapsed or refractory (r/r) B cell NHL after autologous stem cell transplant (ASCT) or at least 2 prior lines of therapy including an anti-CD20 monoclonal antibody and an anthracycline containing chemotherapy regimen. Note: participants with DLBCL transformed from FL must have r/r disease after ASCT or at least 2 prior therapies following transformation irrespective of therapeutic agents. * At least 1 FDG-avid lesion per Lugano Classification criteria at time of enrollment. Exclusion Criteria: * Treatment with any investigational cellular therapy prior to enrollment. Treatment with an approved anti-CD19 CAR T cell therapy in an investigational setting may be permitted after discussion with and approval of the Sponsor. * Progression within 6 weeks of prior anti-CD19 CAR T cell therapy. * Residual toxicities or end-organ damage to vital organs from prior therapy that could put a subject at undue risk based on Investigator's assessment. Toxicities related to prior cytokine release syndrome (CRS) or neurotoxicity must be resolved. * If a subject has received prior anti-CD19 CAR T therapy, development of ≥ Grade 3 CAR T related CRS or ≥ Grade 3 neurotoxicity that in the opinion of the Investigator would cause unacceptable risk of toxicity to the subject upon treatment with bbT369. * Primary central nervous system (CNS) lymphoma or a history or presence of clinically relevant CNS pathology. * Active autoimmune disease requiring systemic immunosuppressive and/or cytotoxic therapy within the past two years. * Treatment with any prior anti-CD79a therapy. * Previous history of an allogeneic bone marrow transplantation. Autologous stem cell transplantation (ASCT) is permitted.